To begin with, we suggest you to subscribe to the Directory Mailing Lists & IRC (follow the link for information on how to subscribe and to access the mail list archives). Listen-in for a while, to see how others make contributions. The you can :

Answer questions posted to the mailing lists.

Contribute to the FAQ or Wiki.

Contribute other documentation patches, either for the website or for the Apache Directory user documentation.

Investigate bugs that have been reported and provide patches where appropriate.

Help with development for the next release of the Directory project and subprojects.